1. Technical Field
The present invention relates to a quantum interference device, an atomic oscillator, an electronic device, and a moving object.
2. Related Art
An atomic oscillator which oscillates based on the atomic energy transfer of an alkaline metal such as rubidium or cesium is known (for example, see JP-A-2009-302118). These types of oscillators are known to possess highly accurate oscillation characteristics that last for a long time.
The operating principle of an atomic oscillator is broadly divided into two systems. The first is a system using a double resonance phenomenon with light or microwaves. The second is a system using a quantum interference effect (coherent population trapping: CPT) with two kinds of light beams having different wavelengths. Recently, atomic oscillators using the quantum interference effect are expected to be mounted on various devices since these types of oscillators can be miniaturized more than an oscillator that uses the double resonance phenomenon.
An atomic oscillator using the quantum interference effect includes, for example, a gas cell in which gaseous metal atoms are sealed, a semiconductor laser which emits laser light having two kinds of resonance light beams having different frequencies to the metal atoms in the gas cell, and a photodetector which detects laser light penetrating the gas cell. In such an atomic oscillator, when a difference in the frequencies of the two kinds of resonance light beams is a specific value, an electromagnetically induced transparency (EIT) phenomenon occurs in which both of the two kinds of resonance light beams are not absorbed into but rather penetrate the metal atoms in the gas cell, and an EIT signal (atomic resonance signal) which is a sharp signal generated with the EIT phenomenon is detected by the photodetector.
The atomic oscillator includes a substrate with circuits provided thereon. Direct current or alternating current at a frequency of equal to or lower than several GHz, and current with several μA to several A may flow through each circuit, as desired.
When interference between predetermined circuits occurs, for example, interference between a circuit through which a small amount of current flows and a circuit through which a great amount of current flows, it is difficult to detect a minute EIT signal with excellent accuracy. As a result, the accuracy of the oscillation frequency of the atomic oscillator decreases.